When safety and durability are non-negotiable, ASME B16.5 socket weld flanges stand out. Designed for high-pressure pipelines, these flanges deliver strong, leak-proof connections while supporting smooth flow and long-term reliability. Perfect for chemical, petrochemical, and industrial applications.
Socket Weld Flange
A Socket Weld (SW) Flange is a type of forged flange used to join a pipe by inserting it into a recessed area (the socket) and then fillet-welding around the hub. Because the pipe is fully supported in the socket, SW flanges provide excellent strength, reliable sealing, and reduced turbulence — making them a high‑performance choice in critical piping systems.
Flange Specification
| Specification | Details |
| Nominal Pipe Size (NPS) | ½″ – 24″ (DN15–DN600) |
| Pressure Class | 150, 300, 400, 600, 900, 1500, 2500 |
| Material Standards | ASTM A105 (Carbon Steel), ASTM A182 (Stainless & Alloy), ASTM A350 LF2 (Low Temp Steel),ASTM A694 (Pipe Line Steel) |
| Manufacturing Standards | ASME B16.5,ASME B16.47,EN 1092-1,JIS B2220 |
Understanding the ASME B16.5 Standard
•According to the ASME B16.5 standard (latest editions), it governs the dimensions, tolerances, pressure-temperature ratings, materials, marking, and testing of pipe flanges and flanged fittings.
•The standard covers flange types including weld neck, slip-on, socket weld, threaded, lap joint, and blind.
•Pressure classes defined under B16.5 include 150, 300, 400,600, 900, 1500, and 2500 lbs (depending on size).
•For socket weld flanges specifically, B16.5 defines applicable sizes, dimensions, and material requirements. According to ASME B16.5‑2017, socket weld flanges may be provided in NPS ½ through NPS 2½ for Class 1500.
Class 300 SW Flange Dimension
| Nominal Pipe Size | A | B | C | D | E | K | F | G | H | I | J | |
| inch | mm | mm | mm | mm | mm | mm | mm | mm | mm | Holes | mm | mm |
| 1/2 | 21.30 | 95.20 | 15.70 | 14.20 | 22.30 | 22.40 | 9.60 | 38.10 | 35.10 | 4 | 15.70 | 66.55 |
| 3/4 | 26.70 | 117.3 | 20.80 | 15.70 | 25.40 | 27.70 | 11.10 | 47.70 | 42.90 | 4 | 19.10 | 82.50 |
| 1 | 33.40 | 123.9 | 26.70 | 17.50 | 26.90 | 34.50 | 12.70 | 53.80 | 50.80 | 4 | 19.10 | 88.90 |
| 11/4 | 42.20 | 133.3 | 35.10 | 19.00 | 26.90 | 43.20 | 14.20 | 63.50 | 63.50 | 4 | 19.10 | 98.60 |
| 11/2 | 48.30 | 155.4 | 40.90 | 20.60 | 30.20 | 49.50 | 15.70 | 69.85 | 73.15 | 4 | 22.30 | 114.3 |
| 2 | 60.30 | 165.1 | 52.60 | 22.30 | 33.20 | 62.00 | 17.50 | 84.00 | 91.90 | 8 | 19.10 | 127.0 |
| 21/2 | 73.00 | 190.5 | 62.70 | 25.40 | 38.10 | 74.70 | 19.00 | 100.0 | 104.6 | 8 | 22.30 | 149.3 |
| 3 | 88.90 | 209.5 | 78.00 | 28.40 | 42.90 | 90.70 | 20.60 | 117.3 | 127.0 | 8 | 22.30 | 168. 1 |
To view dimensions for other pressure ratings, click the link below.
Class 150 Socket Weld Flange Dimension
Class 600 Socket Weld Flange Dimension
Class 1500 Socket Weld Flange Dimension
Socket Weld Flanges Weight Chart（KG）
| Size | 150LB | 300LB | 400LB | 600LB | 900LB | 1500LB | 2500LB |
| 1/2 | 0.91 | 1.36 | 0.91 | 0.91 | 2.72 | 2.72 | 3.18 |
| 3/4 | 0.91 | 1.36 | 1.36 | 1.36 | 2.72 | 2.72 | 4.09 |
| 1 | 0.91 | 1.36 | 1.59 | 1.59 | 3.41 | 3.41 | 5.45 |
| 1 1/4 | 1.14 | 1.82 | 2.04 | 2.04 | 4.54 | 4.54 | 8.17 |
| 1 1/2 | 1.36 | 2.72 | 2.95 | 2.95 | 6.36 | 6.36 | 11.35 |
| 2 | 2.27 | 3.18 | 3.63 | 3.63 | 9.99 | 9.99 | 17.25 |
| 2 1/2 | 3.18 | 4.54 | 5.45 | 5.45 | 14.07 | 16.34 | 24.97 |
| 3 | 3.63 | 5.90 | 6.81 | 6.81 | 16.34 | 21.79 | 37.68 |
| 3 1/2 | 4.99 | 7.72 | 9.53 | 9.53 | — | — | — |
| 4 | 5.90 | 9.99 | 10.90 | 14.98 | 24.06 | 33.14 | 57.66 |
| 5 | 6.81 | — | 14.07 | 28.60 | 37.68 | 59.93 | 95.34 |
| 6 | 8.63 | — | 17.71 | 36.32 | 49.03 | 74.46 | 146.64 |
| 8 | 13.62 | — | 28.60 | 44.04 | 78.09 | 117.13 | 220.19 |
| 10 | 19.52 | — | 41.31 | 80.36 | 111.23 | 197.94 | 419.95 |
| 12 | 29.06 | — | 58.57 | 97.61 | 148.00 | 302.82 | 590.20 |
| 14 | 38.59 | — | 86.71 | 117.59 | 172.52 | — | — |
| 16 | 48.22 | — | 114.86 | 166.16 | 208.39 | — | — |
| 18 | 54.48 | — | 140.74 | 216.10 | 293.74 | — | — |
| 20 | 70.37 | — | 171.61 | 277.85 | 359.57 | — | — |
| 24 | 95.34 | — | 244.71 | 397.70 | 671.92 | — | — |
Flange Material
Carbon Steel Flanges
ASTM A105 carbon steel flanges are the most common, used in general service for water, oil, and gas.
Stainless Steel Flanges
ASTM A182 F304/L and F316/L are standard for corrosive services.
Duplex Stainless Steel Flanges
Grades like A182 F51/F53/S31803 offer superior strength and chloride stress corrosion cracking resistance.
Alloy Steel Flanges
ASTM A182 F11, F22, and F91 are used in high-temperature service, such as power plants and refineries.
Low-Temperature Carbon Steel Flanges
ASTM A350 LF2 is specifically designed for sub-zero temperature applications, preventing brittle fracture in LNG and cryogenic services.
Line Pipe Flanges
ASTM A694 F52, F60, F65 are high-yield flanges designed to mate with pipeline valves and fittings in high-pressure transmission lines.
Socket Weld vs. Slip On Flange
| Feature | Socket Weld Flange (SW) | Slip On Flange (SO) |
| Connection | Pipe inserted into flange socket, fillet-welded | Pipe slips over flange, fillet-welded inside & outside |
| Strength | High | Moderate |
| Leak Resistance | Excellent | Good |
| Flow Disturbance | Minimal | Slightly higher |
| Installation | Requires precise alignment | Easier alignment |
Applications
•Oil & Gas Industry
•Power Plants
•Chemical & Petrochemical
•Cryogenic / LNG
•Pipeline & Transmission
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